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<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    
</body>
<script>
 let arr = [23,566,21,542,78];
 console.log(arr[2]);
 let arr2 = ['tom',34,4,ture,,,,];
 console.log(arr2[4]);
 arr2[4] = null;
 console.log(arr2[4]);
 console.log('-------------');
 console.log(arr.length);
 for(let i = 0;i<arr.length;i++){
    console.log(arr[i]);
 }
 console.log('--------------')
 let score = [89,67,59,90,54,77,83,88.5,43,10,68];
 let max = score[0];
 let sum = 0;
 for(let i = 0;i<score.length;i++){
    if(score[i]>max){
        max = score[i];
    }
    sum +=score[i];
 }
 let avg=sum /score.length;
 console.log('最大值是：'+max);
 console.log('平均分数为：'+avg);
 console.log('----------');
 score[1000] = 88;
 console.log(score[1000]);
 console.log(score.length);
 for(let i = 0;i<score.length;i++){
    console.log(score[i]);
 }
</script>
</html>